Process for the dyeing of cellulose diacetate fibers from basic dye baths containing sulfuric ester salts

ABSTRACT

DYEING OF CELLULOSE DISCETATE FILERS AS WELL AS YARNS, THREADS AND TEXTILE FABRICS MADE THEREOF WITH BASIC DYESTUFFS. THE DYEING IS CARRIED OUT IN THE PRESENCE OF A SALT OF SULFURIC ESTER OF ALIPHATIC ALCOHOL REPRESENTED BY THE FORMULA:   WHEREIN R1 IS A NORMAL ALKYL RADICAL, R2 IS A HYDROGEN ATOM OR A NORMAL ALKYL RADICAL PROVIDED THAT THE SUM OF THE CARBON ATOMS CONTAINED IN THE RADICALS R1 AND R2 IS NINE, AND M IS MEMBER SELECTED FROM THE GROUP OF NA, K AND NH4. THE DYEINGS THUS OBTAINED ARE CHARACTERIZED BY THEIR DEEP AND BRILLIANT SHADES HAVING OUTSTANDING FASTNESS PROPERTIES, ESPECIALLY LIGHT FASTNESS AS COMPARED WITH THOSE OF THE DYEING OBTAINED BY THE USE OF OTHER   SALTS OF SULFURIC ESTERS OF ALIPHATIC ALCOHOLS CONTAINING LESS OR MORE THAN TEN CARBON ATOMS.

June 20, 1972 MINORU OZUTSUMI ETAL 3,6

PROCESS FOR THE DYEING OF CELLULOSE DIACETATE FIBERS FROM BASIC DYE BATHS CONTAINING SULFURIC ESTER SALTS 3 Sheets-Sheet 1 Filed Oct. 6, 1969 Han Dyeing Time min Dyeing Time min.)

MINORU OZUTSUMI, KAZUO KAWAKAMI,

Attorneys June 20, 1972 MINORU OZUTSUMI ETA!- 3,671,132

PROCESS FOR THE DYEING OF CELLULOSE DIACETATE mums FROM BASIC DYE BATHS CONTAINING SULFURIC ESTER SALTS Filed Oct. 6, 1969 3 Sheets-Sheet 2 ptmn 9 L- 50 a A 2 uc 2 f Dyeing Time min.)

jx a A c E 3- I a n:

n 5 1 0 1 5 A an as i s n BY/MMMWM Attorneys June 20, 1972 MINORU OZUTSUMI ET 3,671,182

PROCESS FOR THE DYEING OF CELLULOSE DIACETATE FIBERS FROM BASIC DYE BATHS CONTAINING SULFURIC ESTER SALTS 5 Sheets-Sheet 3 Filed Oct. 6, 1969 FIGS ption /0) Rate of Adsor Anionic Surfactant %0.w.f.

MINORU OZUTSUMI, KAZUO KAWAKAMI, SUMIO ISHIZAKI and MASATOSHI KUROSAWA,

INVENTOR. S

MMAAK AMZSiJ ATTORNEYS United States Patent 3,671,182 PROCESS FOR THE DYEING OF CELLULOSE DI- ACETATE FIBERS FROM BASIC DYE BATHS CONTAINING SULFURIC ESTER SALTS Minoru Ozutsumi, Kazuo Kawakami, Sumio Ishizakl, and

Masatoshi Kurosawa, Tokyo, Japan, assignors to Hodogaya Kagaku Kabushiki Kaisha, Minato-ku, Tokyo,

Japan Filed Oct. 6, 1969, Ser. No. 864,010 Int. Cl. D06p 3/40, 5/04 US. Cl. 8-170 5 Claims ABSTRACT OF THE DISCLOSURE Dyeing of cellulose diacetate fibers as well as yarns, threads and textile fabrics made thereof with basic dyestuffs. The dyeing is carried out in the presence of a salt of sulfuric ester of aliphatic alcohol represented by the formula:

This invention relates to an improved process for the dyeing of cellulose diacetate fibers and more particularly an improved process for the dyeing of cellulose diacetate fibers with basic dyestuffs by the aid of a salt of sulfuric acid ester of alcohol containing 10 carbon atoms.

The diacetate fibers are usually obtained by spinning the acetone solution of cellulose diacetate flakes derived from cellulose triacetate. The degree of acetylation thereof generally is about 50-60%. The fibers may be in the forms of filaments and staple fibers as well as thread, yarn and textile fabric made thereof.

Throughout the specification and claims, the term basic dyestuffs means the water-soluble dyestuffs containing no acidic group and containing coloring moiety which is capable of forming cation in aqueous solution. They embrace not only usual known basic dyestuffs but also the cationic dyestuffs which have recently been developed particularly for dyeing acrylic fibers.

At present cellulose diacetate which is hereafter called simply diacetate is dyed for the most of part with disperse dyestuffs. Dyeing of diacetate fibers with basic dyestuffs had been attempted since the early stage of commercial production diacetate. Because of thermoplasticity, diacetate fibers should be refrained from processing in a high temperature dyeing bath. Furthermore, since diacetate fibers are difficult to swell in a dye bath, impregnation or penetration of dyestuff molecules into the fibers does not take place satisfactorily. This makes it difficult to obtain dyeings of deep shade on diacetate fibers. And actually, there are obtained only the dyeings of medium shade.

Up to date, various attempts have been made to improve the dyeing methods of diacetate fibers and in particular to produce deep dyeings thereon. It was thus proposed, for example, to add an alcohol or organic acid to the dye bath in order to facilitate swelling of diacetate fibers. The method, however, has the obstacle that it re- "Ice quires a relatively large amount of the expensive swelling agent, and despite use of an excess amount of the agent, there is obtained no sufficient penetration of the dyestuff molecules into interior of the fibers, resulting in only faint dyeings without an appreciable improvement in fastness properties.

For these reasons, dyeing of the diacetate fibers with basic dyestuffs was limitedly applied for only obtaining bright shades of dyeings by printing method.

Since, however, the dye-affinity and fastness of the resulting dyeings as well as penetration faculty of the dyestuff molecules into diacetate fibers through dispersion of the dyestuff markedly depend upon the sort of dyestuffs encountered in a preparation of such dispersion system, a special attention should be called to the characteristics of individual dyestuff. This is also applicable particularly to the case in which a blend of various dyestuffs is contemplated to be used for the production of dyeing of mixed colors on the fibers.

Although the higher the absorption velocity of dyestuff, the deeper the dyeings generally obtained, it is thereby susceptible to produce ring-dyed goods owing to an insufficient penetration of the dyestuff. There is thus obtained a dyeing having a poor brightness in shade and the insufiicient fastness properties.

In order to obtain deep shades on the diacetate fibers with dispersion dyestuffs, it is thus necessary to choose a dyestuff which possesses suflicient penetration characteritic or to carry out the dyeing in the presence of a penetration assistant for a relatively long period of time.

Extensive research has been made by the present inventors to establish a method for obtaining deep, level and fast dyeings with basic dyestuffs on diacetate fibers that has no obstacles encountered when dyeing is carried out according to the known arts in which the disperse dyestuffs are employed.

It has been found that excellent dyeings can be obtained with a complex product derived from a cation of basic dyestuff molecule and a salt of sulfuric ester of higher alcohol known as anionic surfactant.

It is surprising that an extraordinary improvement in deep shade is obtained on the diacetate fibers when a salt of sulfuric ester of an alcohol containing 10 carbon atoms is employed for the formation of said dyestuff complex.

The present invention is thus directed to an improved process for dyeing diacetate fibers. The process of the invention is characterized by utilizing an aqueous solution of basic dyestuff in the presence of a salt of sulfuric ester represented by the general formula wherein R is a normal alkyl radical, R is a hydrogen atom or a normal alkyl radical provided that the sum of the carbon atoms contained in the radicals R and R is nine, and M is selected from the group consisting of Na, K and NH In practice of the process of the present invention, a complex product is first formed in a bath from a salt of sulfuric ester of alcohol containing 10 carbon atoms and a cation of the afore-mentioned dye molecule. If necessary, thorough dispersion of the resulting complex may be secured by adding an amount of a nonionic surfactant. Concentration of the salt of sulfuric ester of the alcohol having 10 carbon atoms may be from one to ten moles, preferably from 2 to 5 moles, per mole of the dyestuff.

Exemplary nonionic surfactants preferably used are those having HLB values more than 11. The nonionic surfactant will provide a satisfactory dispersion when it is used in an amount of 50 to of the weight of the specified anionic surfactant to be used. pH value of the dye bath thus obtained is adjusted to 3 to 5, preferably to 4, 'by means of acetic acid.

The dyeing temperature to be employed may be those conventionally used in the dyeing of diacetate.

In the dyeing, especially in the deep shade dyeing according to the process of the present invention, it has been observed that there is obtained a surprisingly superior dye-adsorption on the diacetate fibers as compared with the dyeings which have been obtained with the same basic dyestulf but employing a salt of sulfuric ester of the alcohol containing less or more than 10 carbon atoms. Under microscopical inspection of the lateral section of the dyed fibers according to the present invention, it is found that the dyestuff penetrated to the central area of the fibers.

In the accompanying drawings FIGS. 1-4 are graphical diagrams which demonstrate the excellent dye-adsorptions by diacetate fibers from the dye baths prepared according to the present invention as compared with the dye-adsorptions from the dye baths of control without any surfactant and the dye baths prepared with hitherto known other anionic surfactants.

FIG. involves the graphical diagrams showing that the dye-adsorptions by the diacetate fibers according to the present invention from the dye baths containing 3% dye are higher than those obtained from the baths having the same dye-concentrations in the presence of different quantities of the known anionic surfactant.

Thus the present invention provides deep and fast dyeings with excellent brightness on diacetate fibers with basic dyestuffs that could never be achieved by the hitherto known dyeing processes which employ disperse dyestuffs.

The novel process for the dyeing according to the pres ent invention is also applicable to the printing of textile fabric of diacetate fibers.

The following examples illustrate the invention, percent throughout the examples being by weight based on the weight of the material to be dyed. The dye-adsorption of the fibers was determined by measuring relative absorption values of visible light through the respective solutions of the samples which were taken from the bath initially and periodically in the course of the dyeing and diluted with glacial acetic acid and methanol.

EXAMPLE 1 Three bundles of scoured dry yarns of diacetate filaments were separately dyed at 80 C. for 60 minutes with the dye baths A, B and C hereunder-mentioned, each containing 1.5% of C.I. Basic Yellow 11, C.I. No. 48055, which shows maximum absorption at the wave length of 410 mp.

The dye-adsorptions at the constant temperature of 80 C. in the respective dyeings as inspected are graphically shown in FIG. 1.

(a) pH of the bath was adjusted to 4 with addition of acetic acid. The liquor ratio employed in the dyeing was 1:50.

(b) The dye bath B contained 2% of sodium sulfuric ester of octyl alcohol and 1% of polyethylene glycol oleyl ether. pH of the bath was adjusted to 4 with addition of acetic acid. The liquor ratio employed in the dyeing was 1:50.

(0) The dye bath C contained 2% of sodium salt of sulfuric ester of Z-decanol having the formula and 1% of polyethylene glycol oleyl ether. pH value of the bath was adjusted to 4 with addition of acetic acid. The liquor ratio employed in the dyeing was 1:50.

In FIG. 1, curve A shows 41% of the total of integral dye-adsorption at the constant temperature of 80 C. for 60 minutes from the dye bath A which contained acetic acid alone as additive; curve B shows 57% of the integral dye-adsorption from the dye bath B under the same con- .4 ditions as those employed for curve A, the dye bath B containing a complex compound of the specified dyestulf and sodium salt of sulfuric ester of octyl alcohol contain- .ing 8 carbon atoms as anionic surfactant and also a polyethylene glycol oleyl ether as nonionic surfactant; and finally, curve C shows 94.8% of the integral dye-adsorption from the dye bath C which contained the complex compound of the specified dyestuff and sodium salt of sulfuric ester of Z-decanol having 10 carbon atoms together with polyethylene glycol oleyl ether as additive.

As is evident from the above, the dye-adsorption represented by curve C, which was obtained in accordance with the present invention, is considerably remarkable as compared with those shown by curves A and B.

EXAMPLE 2 In the similar manner as in Example 1, three dyeings were carried out at the temperature of 80 C. for minutes with the 1.5% dye baths A, B and C of C.I. Basic Red 14 which shows maximum absorption at 520 m each of the dye baths having been prepared as hereunder-mentioned.

The dye-adsorptions at the constant temperature of 80 C. for 60 monutes thus observed are graphically shown in FIG. 2.

(a) The dye bath A was prepared in the same manner as in the bath A in Example 1.

(b) The dye bath B contained 2% of sodium salt of lauryl sulfate and 1% of polyethylene glycol nonylphenol ether. pH value of the bath was adjusted to 4 with addition of acetic acid. The liquor ratio employed in the dyeing was 1:50.

(c) The dye bath C contained 2% of sodium salt of n-decyl sulfate and 1% of polyethylene glycol nonylphenol ether. The liquor ratio employed in the dyeing was 1:50. pH value of the bath was adjusted to 4 with addition of acetic acid.

As is seen in FIG. 2, curve A shows 42% integral dyeadsorption from the dye bath A which contained only acetic acid, and curve B shows 84.6% integral dye-absorption from the dye bath B which contained sodium salt of sulfuric ester of lauryl alcohol containing twelve carbon atoms. Said dye-absorption value amounts to twice as much as that of curve A. Whereas curve C shows 90.6%

integral dye-absorption from the dye bath C which contained sodium salt of sulfuric ester of n-decyl sulfate.

As is evident from the above, the superior dye-absorption was attained by the use of the dye bath C as compared with the dye-adsorption obtained by the use of the dye bath B which contained sodium salt of lauryl sulfate as anionic surfactant.

EXAMPLE 3 The dye-absorptions were observed in the dyeings at the constant temperature of C. for 60 minutes according to Examples 1 and 2 with the dye baths A, B and C, each containing 1.5% of C.I. Basic Blue 3, C.I. No. 51005, having maximum absorption at 640 m (a) The dye bath A was prepared in the same manner as in the bath A of Example 1. pH of the bath was made up to 4 with addition of acetic acid. The liquor ratio of 1:50 was employed in the dyeing.

(b) The dye bath B was prepared by adding 2% sodium salt of tetradecyl sulfate and 1% polyethylene glycol oleyl ether. pH of the liquor was made up to 4 with addition of acetic acid. The liquid ratio of 1:50 was employed in the dyeing.

(c) The dye bath C was prepared by adding 2% sodium salt of n-decyl sulfate and 1% polyethylene glycol oleyl ether. pH of the liquor was made u to 4 by means of acetic acid. The liquor ratio of 1:50 was employed in the dyeing.

The results observed are graphically shown in FIG. 3.

In FIG. 3, the integral dye-absorption in curve C is 90.3% which is fairly eminent as compared with the integral dye-adsorption of 58.2% as shown in curve B which was obtained with the bath B previously prepared with sodium salt of sulfuric ester of tetradecyl alcohol containing 14 carbon atoms; and finally the integral dyeadsorption of 38.3% is found in curve A which was obtained from the bath A previously prepared only with acetic acid.

From the above, it is noted that there is a remarkable difference between the above-mentioned salts of alkyl sulfate with respect to the promoting or enhancing property of the dye-adsorption.

EXAMPLE 4 In accordance with the procedure disclosed in the preceding examples, the dye-adsorptions in the dyeings at the constant temperature of 80 C. for 60 minutes were observed by using the dye baths A, B and C, each containing 1.5% of C.I. Basic Red 13 C.I. No. 48,015 which possesses maximum absorption at 530 me. For the sake of comparison, sodium salt of sulfuric ester of stearyl alcohol which contains 18 carbon atoms was used as anionic surfactant in the under-mentioned dye bath B. The dye baths A, B and C were prepared as follows:

(a) The dye bath A was same as the bath A in Example 1. pH of the bath was made up to 4 with acetic acid. The liquor ratio of 1:50 was employed.

(b) The dye bath B was prepared by adding 2% sodium salt of stearyl sulfate and 1% polyethylene glycol nonylphenol ether. pH of the liquor was made up to 4 with addition of acetic acid. The liquor ratio of 1:50 was employed in the dyeing.

(c) The dye bath C was prepared with 2% sodium salt of n-decyl sulfate and 1% polyethylene glycol nonylphenol ether. pH of the liquor was made up to 4 with addition of acetic acid. The liquor ratio of 1:50 was used in the dyeing.

The results observed are graphically shown in FIG. 4.

In FIG. 4, it is noted that 72.8% integral dye-absorption as shown in curve B was obtained from the dye bath B which contained as anion surfactant sodium salt of sulfuric ester of stearyl alcohol containing 18 carbon atoms. The dye-adsorption is considerably higher than the 54.8% integral dye-adsorption in curve A, which was obtained from the dye bath A prepared only with acetic acid.

A more extreme improvement of 87.7% dye-absorption was obtained in curve C from the dye bath C which was prepared with sodium salt of n-decyl sulfate according to the process of the present invention.

As shown in the data obtained in the above examples, the adsorption of the basic dyes by diacetate fibers is considerably improved when the process for dyeing is carried out in accordance with the present invention in which a salt of sulfuric ester of straight or branched decyl alcohol having 10 carbon atoms is employed in place of the salts of sulfuric esters of alpihatic alcohols which contain, for example, 8, 12, 14 or 18 carbon atoms.

The following Example 5 and Table I will serve to illustrate comparative effects of the anionic surfactants on the dye-adsorptions by diacetate fibers in deep shade dyeings with the following seven cationic dyestuff dye baths. One of the nonionic surfactants was sodium salt of sulfuric ester of n-decyl alcohol containing carbon atoms; the other was sodium salt of sulfuric ester of lauryl alcohol containing 12 carbon atoms, which had been proved as most effective amongst the similar sodium salts of sulfuric esters of aliphatic alcohols containing carbon atoms other than 12 carbon atoms with exception of the decyl alcohol.

EXAMPLE 5 Four groups A A B and B of the dye baths each consisting of seven baths were prepared by dissolving the respective seven basic dyestuffs, namely, C.I. Basic Yellow 11; C.I. Basic Orange 21; C.I. No. 48,035; C.I. Basic Red 14; C.I. Basic Red 13; C.I. Basic Blue 67; C.I. Basic Blue 3, C.I. Basic Green 1 and C.I. No. 42,040. The respective seven baths of the groups A and A contained 3% of the respective dyestuffs, and the respective seven baths of the groups B and B contained 5% of the respective dyestuffs.

To the respective seven baths of group A were added 3% of sodium salt of lauryl sulfate as anionic surfactant, whereas to the respective seven baths of the other group A were added 3% of the sodium salt of n-decyl sulfate as anionic surfactant.

To the respective seven baths of the group B were added 5% of the afore-mentioned lauryl sulfate an anionic surfactant, whereas to the respective seven baths of the group B were added 5% of the afore-mentioned n-decyl anionic surfactant.

One percent of polyethylene glycol oleyl ether as nonionic surfactant was further added to each of the baths of these 4 groups, and pH values of the dye liquors thus obtained were adjusted to 4 with addition of acetic acid. The dyeing was conducted at the liquor ratio of 1:50, starting from the temperature of 50 C. The temperature was gradually raised to C., and the dyeing was conducted at that temperature for 50 minutes.

The results obtained are summarized in Table I.

TABLE L-COMPARISON OF DYE-ADSORPTIONS EN- HANCED BY THE AID OF SODIUM SALT OF LAURYL AND n-DECYL SULFATES Dye-adsorption Dyeing con- (percent) centration I (percent Lauryl n-Decyl Baslc dyestuff o.w.f.) surfactant surfactant C.I. Basic Yellow 11 (410 may..- 3 73.8 94.4 5 50. 3 92. 2

0.1. Basic Orange 21 (485 m 3 71. 5 96. 0 5 53. 5 92. 6

C.I. Basic Red 14 (52011111.) 3 71. 5 89.9 5 47. 6 88. 6

C.I. Basie Red 13 (530 m 3 73. 4 88. 5 5 47. 4 85. 3

0.1. Basic Blue 67 (610 my) 3 29. 3 86. 0 5 13. 2 67. 0

C.I. Basic Blue 3 (640 my) 3 63. 4 87. 3 5 40. 4 82. 9

0.1. Basic Green 1 (630 mp.) 3 38.0 77. 0 5 18. 9 76. 5

It is noted in Table I that with the sulfuric ester salt of lauryl alcohol containing 12 carbon atoms, the percent dyestutf adsorbed by the diacetate threads depresses as the increase in concentrations of the dyestulf in the bath. Deep shades of dyeings could therefore not be obtained by the aid of the said compound. On the contrary, with the salt of sulfuric ester of decyl alcohol containing 10 carbon atoms according to the present invention, there occurred only slight depression in the percent adsorption of the dyestuffs. The deep shades of dyeing were thus obtained with the said compound as the dyeing assistant. The following example will serve to explain effects on the percent adsorptions of the dyestuffs by the diacetate material in the presence of varied amounts of the anionic surfactants.

EXAMPLE 6 Two groups A and B each consisting of six dye baths were prepared by dissolving respectively 3% of C.I. Basic Red 14 which shows maximum adsorption at 520 mp. wave length.

To five baths of the group A were added respectively 1, 2, 3, 4 and 5% of sodium salt of lauryl sulfate as anionic surfactant which is the same as that employed in Example 5. Likewise, to five dye baths of the group B were respectively added 1, 2, 3, 4 and 5% of sodium salt of n-decyl sulfate.

Twelve bundles of threads of diacetate filaments were separately dyed with each of the above-obtained twelve dye baths under dyeing conditions hereunder-mentioned.

The effects of the added anionic surfactants as well as the variations of the quantities of the added anionic surfactants on the dye-adsorption of the threads were observed.

The dyeing conditions:

(a) Sodium salt of lauryl sulfate as anionic surfactant was used in the respective amounts as above-mentioned.

(b) Sodium salt of n-decyl sulfate were used in the respective amounts as above-mentioned.

To each of the twelve dye baths were further added 1% of polyethylene glycol oleyl ether, a nonionic surfactant.

pH of the dye baths were adjusted to 4 with addition of acetic acid. The dyeing was conducted in the liquor ratio of 1:50, starting from the dyeing temperature of 50 C. The temperature was then elevated to 80 C. within 30 minutes, and the dyeing was conducted at that temperature for 60 minutes. The results observed are graphically shown in FIG. 5.

In FIG. 5, curve A shows the respective integral dyeadsorptions obtained by the dyeings with the six dye baths of the group A, each of which contained the afore-mentioned amounts of sodium salt of sulfuric ester of lauryl alcohol containing 12 carbon atoms, with exception of one of them as control.

As is seen in curve A, the high dye-adsorptions amounting 81% were obtained with the two baths containing respectively 1% and 2% of the said anionic surfactant.

It was, however, found that these dyeings were washed out to a considerable extent when the dyed materials were rinsed with water and then subjected to soaping. The phenomenon is apparently due to feeble and superficial dyeings merely on external portions of the filaments.

The dyeings obtained with the four baths containing respectively 3, 4 and 5% of the said anionic surfactant did not almost come out when rinsed with water followed by soaping. This fact shows that they are fast dyeings. However, the individual integral dye-adsorptions lowered successively as the concentrations of that surfactant in the baths increased.

Contrary to the above, curve B in FIG. 5, which shows the individual integral dye-adsorptions obtained by the dyeing with the six baths of the group B, each of the baths, with exception of one of them, containing the aforementioned individual amounts of sodium salt of decyl sulfate according to the present invention, successively increased as the concentrations of the surfactant in the bathes increased rather than decreased as those in curve A. This phenomenon proves that the specified salt of decyl sulfate as previously substantiated in Example 5 shows an outstanding effect of improving dyeing property of diacetate fibers with basic dyestuffs.

EXAMPLE 7 Light fastness properties of the dyeings produced on the bundles of the threads of diacetate filaments were measured with a Fade-Ometer. The dyeings were obtained by using three dye baths A, B and C which had been prepared by dissolving respectively 5% of the following basic dyestuffs:

C.I. Basic Yellow 11 Cl. Basic Red 13 C.I. Basic Blue 3 Each of the dye baths thus obtained were divided into three portions.

To each of the first portions were added a definite amount of a salt of lauryl sulfate as anionic surfactant.

To each of the second portions were added a definite amount of a salt of decyl sulfate, while each of the third portions were retained as control without adding any anionic surfactant.

pH values of all these portions were adjusted to 4 by means of acetic acid.

The dyeing was conducted in accordance with the manner disclosed in the foregoing Example 5.

8 The dyeings thus obtained were subjected to light fastness test by means of a Fade-*Ometer A.A.T.C.C. 16A- 1964 provided with a carbon arc lamp. The results thus obtained are given in Table II.

As is seen from the data in Table II, all the dyeings obtained with the dye baths containing no anionic surfactant and containing only acetic acid exhibited light fastness of around 4. The dyeings obtained with the dye baths which contained the salt of lauryl sulfate exhibited better light fastnesses, about one grade higher than that of the dyeings obtained with the dye baths without the aforementioned anionic surfactant.

The Colour Index numbers of the above set-forth dyestuffs are found in the Colour Index, 2nd ed. 1956, vol. 1, published by the A.A.T.C.C., Lowell, Mass.

Finally, the dyeings with the dye baths which contained the salt of decyl sulfate exhibited the light fastnesses 0.5-1 grade higher than that of the aforementioned dyeings which were obtained with the dye baths containing the salt of lauryl sulfate.

What we claim is:

1. A process for dyeing cellulose diacetate fibers comprising dyeing the fibers with an aqueous solution of a basic dyestuff in admixture with a salt of an alkyl sulfate of the formula R2 Rr( JHOSOaM wherein R is a normal alkyl radical, R is a hydrogen atom or a normal alkyl radical, provided that the sum of carbona toms in R and R is nine, and M is Na, K or NH 2. The process as claimed in claim 1 wherein the sodium salt of n-decyl sulfate is used as the salt of an alkyl sulfate.

3. The process as claimed in claim 1 wherein the sodium salt of the sulfuric ester of Z-decanol is used as the salt of an alkyl sulfate.

4. The process as claimed in claim 1 wherein the salt of an alkyl sulfate is of the formula CH (CH -OSO M or duaomn-brnosom wherein M is Na, K or NH and is utilized in an amount of 1-10 moles per mole of destuff.

5. The process as claimed in claim 4 wherein the admixture of dyestulf and salt contains a nonionic surfactant having a HLB value greater than 11 in an amount of 50-100% by weight of the salt, and the pH of the dyeing system is maintained at 3-5.

References Cited UNITED STATES PATENTS 3,057,674 10/1962 Musser 8-83 2,049,087 7/1936 Sibley 85 FOREIGN PATENTS 597,683 11/1955 Canada.

GEORGE F. LESMES, Primary Examiner T. J. HERBERT, JR., Assistant Examiner 

